AHP Unit III PPT- Cardiovascular and Lymphatic system

Cardiovascular
Components of Blood and functions
Blood Groups and importance
Structure of Heart
Conducting System of Heart
Properties of Cardiac Muscle
Cardiac Cycle - Heart Beat
Types of Blood vessel
Regulation of Heart rate and Blood pressure.
Lymphatic
Parts and Functions of Lymphatic systems
Types of Lymphatic organs and vessels

1. Unit – III CARDIOVASCULAR AND LYMPHATIC SYSTEM

2. Topic to be covered in Unit – III Cardiovascular Components of Blood and functions Blood Groups and importance Structure of Heart Conducting System of Heart Properties of Cardiac Muscle Cardiac Cycle - Heart Beat Types of Blood vessel Regulation of Heart rate and Blood pressure. Lymphatic Parts and Functions of Lymphatic systems Types of Lymphatic organs and vessels

3. Session 1

4. Objective : To Learn about organs involved in the circulatory system and the components of blood Learning Outcome: Appraise the importance of blood cells in the human body List the components of blood

5. Blood Blood is a connective tissue in fluid form. It is considered as the ‘fluid of life’ because it carries oxygen from lungs to all parts of the body and carbon dioxide from all parts of the body to the lungs. It is known as ‘fluid of growth’ because it carries nutritive substances from the digestive system and hormones from endocrine gland to all the tissues . The blood is also called the ‘fluid of health’ because it protects the body against the diseases and gets rid of the waste products and unwanted substances by transporting them to the excretory organs like kidneys .

6. COMPOSITION OF BLOOD AND FUNCTION: Blood contains the blood cells which are called formed elements and the liquid portion known as plasma. Blood Cells Three types of cells are present in the blood: Red blood cells or erythrocytes White blood cells or leukocytes Platelets or thrombocytes.

7. PLASMA Plasma is a straw-colored clear liquid part of blood. It contains 91% to 92% of water and 8% to 9% of solids. The solids are the organic and the inorganic substances Table 7.1 gives the normal values of some important substances in blood. SERUM Serum is the clear straw-colored fluid that oozes from blood clot. When the blood is shed or collected in a container, it clots. In this process, the fibrinogen is converted into fibrin and the blood cells are trapped in this fibrin forming the blood clot. After about 45 minutes, serum oozes out of the blood clot.

8. FUNCTIONS OF BLOOD 1 . NUTRITIVE FUNCTION 2. RESPIRATORY FUNCTION 3. EXCRETORY FUNCTION 4. TRANSPORT OF HORMONES AND ENZYMES 5. REGULATION OF WATER BALANCE 6. REGULATION OF ACID-BASE BALANCE 7. REGULATION OF BODY TEMPERATURE 8. STORAGE FUNCTION 9. DEFENSIVE FUNCTION

9. Properties of Blood Color : Blood is red in color. Arterial blood is scarlet red because it contains more oxygen and venous blood is purple red because of more carbondioxide . Volume : Average volume of blood in a normal adult is 5 L. In a newborn baby, the volume is 450 ml. It increases during growth and reaches 5 L at the time of puberty. In females, it is slightly less and is about 4.5 L. It is about 8% of the body weight in a normal young healthy adult, weighing about 70 kg . Reaction and pH: Blood is slightly alkaline and its pH in normal conditions is 7.4 .

10. Specific gravity (Relative Density): Specific gravity of total blood : 1.052 to 1.061 Specific gravity blood cells : 1.092 to 1.101 Specific gravity of plasma : 1.022 to 1.026 Viscosity : Blood is five times more viscous than water . It is mainly due to red blood cells and plasma proteins . Properties of Blood

11. Session 2

12. Objective : To Learn about organs involved in the circulatory system and the components of blood Learning Outcome: Appraise the importance of blood cells in the human body & Blood grouping

13. Blood Grouping BLOOD GROUPS When blood from two individuals is mixed, sometimes clumping (agglutination) of RBCs occurs. This clumping is because of the immunological reactions. ABO Blood Groups: Determination of ABO blood groups depends upon the immunological reaction between antigen and antibody. Landsteiner found two antigens on the surface of RBCs and named them as A antigen and B antigen. These antigens are also called agglutinogens because of their capacity to cause agglutination of RBCs. He noticed the corresponding antibodies or agglutinins in the plasma and named them anti-A or α-antibody and anti-B or β-antibody . However , a particular agglutinogen and the corresponding agglutinin cannot be present together. If present , it causes clumping of the blood. Based on this, Karl Landsteiner classified the blood groups. Later it became the ‘Landsteiner Law’ for grouping the blood.

14. Landsteiner Law Landsteiner law states that: 1 . If a particular agglutinogen (antigen) is present in the RBCs, corresponding agglutinin (antibody) must be absent in the serum. 2 . If a particular agglutinogen is absent in the RBCs, the corresponding agglutinin must be present in the serum . Though the second part of Landsteiner law is a fact, it is not applicable to Rh factor.

15. „ Blood Group Systems More than 20 genetically determined blood group systems are known today. But , Landsteiner discovered two blood group systems called the ABO system and the Rh system. These two blood group systems are the most important ones that are determined before blood transfusions .

16. ABO System Based on the presence or absence of antigen A and antigen B, blood is divided into four groups : 1. ‘A’ group 2. ‘B’ group 3. ‘AB’ group 4. ‘ O’ group .

17. Determination OF ABO GROUP Determination of the ABO group is also called blood grouping , blood typing or blood matching. Principle of Blood Typing – Agglutination Blood typing is done on the basis of agglutination. Agglutination means the collection of separate particles like RBCs into clumps or masses. Agglutination occurs if an antigen is mixed with its corresponding antibody which is called isoagglutinin . Agglutination occurs when A antigen is mixed with anti-A or when B antigen is mixed with anti-B.

18. Determination OF ABO GROUP

19. Rh FACTOR Rh factor is an antigen present in RBC. This antigen was discovered by Landsteiner and Wiener. It was first discovered in Rhesus monkey and hence the name ‘Rh factor’. There are many Rh antigens but only the D antigen is more antigenic in human. The persons having D antigen are called ‘Rh positive’ and those without D antigen are called ‘Rh negative’. Among Indian population, 85% of people are Rh positive and 15% are Rh negative. Percentage of Rh positive people is more among black people. Rh group system is different from ABO group system because , the antigen D does not have corresponding natural antibody (anti-D). However , if Rh positive blood is transfused to a Rh negative person anti-D is developed in that person. On the other hand, there is no risk of complications if the Rh positive person receives Rh negative blood.

20. Session 3

21. Objective : To familiarize about the anatomy and physiology of cardiovascular system Learning Outcome: Illustrate different sections of heart Elucidate the function of heart List the components of conductive system in heart

22. Cardiovascular System Cardiovascular system includes heart and blood vessels . Heart pumps blood into the blood vessels. Blood vessels circulate the blood throughout the body. Blood transports nutrients and oxygen to the tissues and removes carbon dioxide and waste products from the tissues.

23. Heart Heart is a muscular organ that pumps blood throughout the circulatory system. It is situated in between two lungs in the mediastinum. It is made up of four chambers, two atria and two ventricles. The musculature of ventricles is thicker than that of atria. Force of contraction of heart depends upon the muscles.

24. STRUCTURE OF HEART : Right Side of the Heart Left Side of The Heart Septa of The Heart Layers of Wall of the Heart Pericardium Fibrous layer Serous layer Myocardium Valves of the Heart Atrioventricular Valves Semilunar Valves

25. Right Side of the Heart Right side of the heart has two chambers, right atrium and right ventricle. Right atrium is a thin walled and low pressure chamber . It has got the pacemaker known as sinoatrial node that produces cardiac impulses and atrioventricular node that conducts the impulses to the ventricles . Right atrium receives venous (deoxygenated) blood via two large veins: 1. Superior vena cava that returns venous blood from the head, neck and upper limbs 2. Inferior vena cava that returns venous blood from lower parts of the body (Fig. 89.1). Right atrium communicates with right ventricle through tricuspid valve. Wall of right ventricle is thick. Venous blood from the right atrium enters the right ventricle through this valve. From the right ventricle, pulmonary artery arises. It carries the venous blood from right ventricle to lungs. In the lungs, the deoxygenated blood is oxygenated.

26. Left side of the heart has two chambers, left atrium and left ventricle. Left atrium is a thin walled and low pressure chamber. It receives oxygenated blood from the lungs through pulmonary veins. This is the only exception in the body, where an artery carries venous blood and vein carries the arterial blood. Blood from left atrium enters the left ventricle through mitral valve (bicuspid valve). Wall of the left ventricle is very thick. Left ventricle pumps the arterial blood to different parts of the body through systemic aorta. Left Side of the Heart

27. Septa Of The Heart Right and left atria are separated from one another by a fibrous septum called interatrial septum. Right and left ventricles are separated from one another by interventricular septum. The upper part of this septum is a membranous structure, whereas the lower part of it is muscular in nature.

28. „ Layers Of Wall Of The Heart Heart is made up of three layers of tissues : Outer pericardium Middle myocardium Inner endocardium

29. Structure of heart

30. Function of Heart Blood (poor with oxygen) flows from the body to the right atrium and then to the right ventricle. The right ventricle pump the blood to the lung. Blood (rich with oxygen) flows from the lung into the left atrium and then to the left ventricle. The left ventricle pump the blood to the rest of the body . Diastole: is the resting or filling phase (atria chamber) of the heart cycle. Systole: is the contractile or pumping phase (ventricle chamber) of the heart cycle. The electrical events is intrinsic to the heart itself.

31. CONDUCTIVE SYSTEM IN HUMAN HEART : AV node Bundle of His Right and left bundle branches Purkinje fibers.

32. CONDUCTIVE SYSTEM IN HUMAN HEART SA node activates first the right and then the left atrium. AV node delays a signal coming from the SA node before it distribute it to the Bundle of His. Bundle of His and Purkinie fibers activate the right and left ventricles A typical QRS amplitude is 1-3 mV The P-wave shows the heart's upper chambers (atria) contracting ( depol .) The QRS complex shows the heart's lower chambers (ventricles) contracting The T-wave shows the heart's lower chambers (ventricles) relaxing ( repol .) The U-wave believed to be due repolarization of ventricular papillary muscles. P-R interval is caused by delay in the AV node S-T segment is related to the average duration of the plateau regions of the individual ventricular cells.

33. Session 4

34. Objective : To understand the characteristics and structure of cardiac muscle Learning Outcome: List the properties of Cardiac Muscle State Excitability & Rhythmicity State conductivity & Contractility

35. Cardiac Muscle Heart is made up of three layers of tissues: Outer pericardium Middle myocardium Inner endocardium PERICARDIUM Pericardium is the outer covering of the heart. It is made up of two layers: i. Outer parietal pericardium ii. Inner visceral pericardium. The space between the two layers is called pericardial cavity or pericardial space and it contains a thin film of fluid.

36. i. Outer Parietal Pericardium Parietal pericardium forms a strong protective sac for the heart. It helps also to anchor the heart within the mediastinum. Parietal pericardium is made up two layers: a. Outer fibrous layer b. Inner serous layer. Fibrous layer Fibrous layer of the parietal pericardium is formed by thick fibrous connective tissue. It is attached to the diaphragm and it is continuous with tunica adventitia (outer wall) of the blood vessels, entering and leaving the heart. It is attached with diaphragm below. Because of the fibrous nature, it protects the heart from over stretching.

37. Serous layer Serous layer is formed by mesothelium, together with a small amount of connective tissue. Mesothelium contains squamous epithelial cells which secrete a small amount of fluid, which lines the pericardial space. This fluid prevents friction and allows free movement of heart within pericardium, when it contracts and relaxes. The total volume of this fluid is only about 25 to 35 mL. ii . Inner Visceral Pericardium Inner visceral pericardium lines the surface of myocardium. It is made up of flattened epithelial cells. This layer is also known as epicardium .

38. MYOCARDIUM Myocardium is the middle layer of wall of the heart and it is formed by cardiac muscle fibers or cardiac myocytes . Myocardium forms the bulk of the heart and it is responsible for pumping action of the heart. Unlike skeletal muscle fibers, the cardiac muscle fibers are involuntary in nature . Myocardium has three types of muscle fibers: i. Muscle fibers which form contractile unit of heart ii. Muscle fibers which form pacemaker iii. Muscle fibers which form conductive system.

39. i. Muscle Fibers which Form Contractile Unit of Heart These cardiac muscle fibers are striated and resemble the skeletal muscle fibers in structure. Cardiac muscle fiber is bound by sarcolemma . It has a centrally placed nucleus . Myofibrils are embedded in the sarcoplasm. Sarcomere of the cardiac muscle has all the contractile proteins , namely actin, myosin, troponin and tropomyosin . Sarcotubular system in cardiac muscle is similar to that of skeletal muscle. Important difference between skeletal muscle and cardiac muscle is that the cardiac muscle fiber is branched and the skeletal muscle is not branched.

40. Intercalated disk Intercalated disk is a tough double membranous structure, situated at the junction between the branches of neighboring cardiac muscle fibers. It is formed by the fusion of the membrane of the cardiac muscle branches (Fig. 89.2). Intercalated disks form adherens junctions, which play an important role in the contraction of cardiac muscle as a single unit.

41. Syncytium Syncytium means tissue with cytoplasmic continuity between adjacent cells. However , cardiac muscle is like a physiological syncytium , since there is no continuity of the cytoplasm and the muscle fibers are separated from each other by cell membrane. At the sides , the membranes of the adjacent muscle fibers fuse together to form gap junctions. Gap junction is permeable to ions and it facilitates the rapid conduction of action potential from one fiber to another . Because of this, all the cardiac muscle fibers act like a single unit , which is referred as syncytium . Syncytium in human heart has two portions, syncytium of atria and the syncytium of ventricles. Both the portions of syncytium are connected by a thick non-conducting fibrous ring called the atrioventricular ring .

42. ii. Muscle Fibers which Form the Pacemaker Some of the muscle fibers of heart are modified into a specialized structure known as pacemaker . These muscle fibers forming the pacemaker have less striation . Pacemaker Pacemaker is structure in the heart that generates the impulses for heart beat. It is formed by pacemaker cells called P cells . Sinoatrial ( SA) node forms the pacemaker in human heart. iii. Muscle Fibers which Form Conductive System Conductive system of the heart is formed by modified cardiac muscle fibers. Impulses from SA node are transmitted to the atria directly. However , the impulses are transmitted to ventricles through various components of conducting system

43. ENDOCARDIUM Endocardium is the inner most layer of heart wall. It is a thin , smooth and glistening membrane. It is formed by a single layer of endothelial cells, lining the inner surface of the heart. Endocardium continues as endothelium of the blood vessels.

44. Features of Cardiac Muscles

45. PROPERTY OF CARDIAC MUSCLE Excitability Rhythmicity Conductivity Contractility

46. EXCITABILITY Definition Excitability is defined as the ability of a living tissue to give response to a stimulus. In all the tissues, initial response to a stimulus is electrical activity in the form of action potential. It is followed by mechanical activity in the form of contraction, secretion, etc. Electrical Potentials In Cardiac Muscle

47. ELECTRICAL POTENTIALS IN CARDIAC MUSCLE Resting Membrane Potential Resting membrane potential in: Single cardiac muscle fiber : – 85 to – 95 mV Sinoatrial (SA) node : – 55 to – 60 mV Purkinje fibers : – 90 to – 100 mV . Action Potential Action potential in cardiac muscle is different from that of other tissues such as skeletal muscle, smooth muscle and nervous tissue. Duration of the action potential in cardiac muscle is 250 to 350 msec (0.25 to 0.35 sec). Phases of action potential Action potential in a single cardiac muscle fiber occurs in four phases: 1. Initial depolarization 2. Initial repolarization 3. A plateau or final depolarization 4. Final repolarization.

48. RHYTHMICITY Definition Rhythmicity is the ability of a tissue to produce its own impulses regularly. It is also called autorhythmicity or self-excitation. Property of rhythmicity is present in all the tissues of heart. However, heart has a specialized excitatory structure, from which the discharge of impulses is rapid. This specialized structure is called pacemaker . From here, the impulses spread to other parts through the specialized conductive system.

49. CONDUCTIVITY Human heart has a specialized conductive system, through which impulses from SA node are transmitted to all other parts of the heart (Fig. 90.4 ). Components of Conductive System in Human Heart AV node Bundle of His Right and left bundle branches Purkinje fibers

50. CONTRACTILITY Contractility is ability of the tissue to shorten in length (contraction ) after receiving a stimulus. Various factors affect the contractile properties of the cardiac muscle. Following are the contractile properties: ALL-OR-NONE LAW „STAIRCASE PHENOMENON „SUMMATION OF SUBLIMINAL STIMULI „REFRACTORY PERIOD According to all-or-none law, when a stimulus is applied, whatever may be the strength, the whole cardiac muscle gives maximum response or it does not give any response at all. Below the threshold level, i.e. if the strength of stimulus is not adequate, the muscle does not give response.

51. Session 5 https://www.youtube.com/watch?v=IS9TD9fHFv0

52. Objective : To get familiarize with the different events of cardiac cycle Learning Outcome: List different events of cardiac cycle Illustrate the atrial, ventricular event of cardiac cycle

53. CARDIAC CYCLE Definition Cardiac cycle is defined as the succession of ( sequence of ) coordinated events taking place in the heart during each beat. Each heartbeat consists of two major periods called systole and diastole. During systole, heart contracts and pumps the blood through arteries. During diastole, heart relaxes and blood is filled in the heart . All these changes are repeated during every heartbeat , in a cyclic manner.

54. Events of Cardiac Cycle ATRIAL EVENTS Atrial events are divided into two divisions: 1. Atrial systole = 0.11 (0.1) sec 2. Atrial diastole = 0.69 (0.7) sec . VENTRICULAR EVENTS Ventricular events are divided into two divisions: 1. Ventricular systole = 0.27 (0.3) sec 2. Ventricular diastole = 0.53 (0.5) sec. Events of cardiac cycle are classified into two: 1. Atrial events 2. Ventricular events. Divisions And Duration Of Cardiac Cycle When the heart beats at a normal rate of 72/minute, duration of each cardiac cycle is about 0.8 second In clinical practice, the term ‘systole’ refers to ven­tricular systole and ‘diastole’ refers to ventricular diastole. Ventricular systole is divided into two subdivisions and ventricular diastole is divided into five subdivisions.

55. Events of Cardiac Cycle

56. Events of Cardiac Cycle

57. Session 6

58. Objective : To Learn about heart sounds and its importance in diagnosing certain heart disorder. Learning Outcome: Relate the heart sound production with cardiac events

59. Heart sounds Heart sounds are the sounds produced by mechanical activities of heart during each cardiac cycle. Heart sounds are produced by: 1. Flow of blood through cardiac chambers 2. Contraction of cardiac muscle 3. Closure of valves of the heart.

60. Different Heart Sounds Heart sounds are heard by placing the ear over the chest or by using a stethoscope or microphone. These sounds are also recorded graphically. Four heart sounds are produced during each cardiac cycle : First heart sound Second heart sound Third heart sound Fourth heart sound

61. Heart sounds First and second heart sounds are called classical heart sounds and are heard by using the stethoscope. These two sounds are more prominent and resemble the spoken words ‘LUB, (or LUBB) and ‘DUBB’ ( or DUP ), respectively. Third heart sound is a mild sound and it is not heard by using stethoscope in normal conditions. But it can be heard by using a microphone. Fourth heart sound is an inaudible sound. It becomes audible in pathological conditions only. This sound is studied only by graphic registration , i.e. the phonocardiogram.

62. Heart Sounds

63. „ Importance Of Heart Sounds Study of heart sounds has important diagnostic value in clinical practice because alteration in the heart sounds indicates cardiac diseases involving valves of the heart .

64. Cardiac Murmur Cardiac murmur is the abnormal or unusual heart sound . It is also called abnormal heart sound or cardiac bruit . Cardiac murmur is heard by stethoscope, along with normal heart sounds. Cardiac murmur is heard by placing chest piece of stethoscope over the auscultatory areas. Murmur due to disease of a particular valve is heard well over the auscultatory area of that valve. Sometimes , the murmur is felt by palpation as ‘thrills’. In some patients, murmur is heard without any aid, even at a distance of few feet away from the patient.

65. Causes Of Murmur Cardiac murmur is produced because of change in the pattern of blood flow. Normally , blood flows in streamline through the heart and blood vessels. However , during abnormal conditions like valvular diseases , the blood flow becomes turbulent. It produces the cardiac murmur.

66. Valvular Diseases Valvular diseases are of two types: 1. Stenosis 2. Incompetence. 1. Stenosis Stenosis means narrowing of heart valve. Blood flows rapidly with turbulence through the narrow orifice of the valve , resulting in murmur . 2. Incompetence Incompetence refers to weakening of the heart valve. When the valve becomes weak, it cannot close properly. It causes back flow of blood, resulting in turbulence. This disease is also called regurgitation or valvular insufficiency .

67. Session 7 BLOOD VESSEL

68. Blood Vessel The heart pumps blood into vessels that vary in structure, size and function, and there are several types : arteries arterioles capillaries venules veins

69. Arteries and arterioles These are the blood vessels that transport blood away from the heart. They vary considerably in size and their walls consist of three layers of tissue (Fig. 5.3 ) tunica adventitia or outer layer of fibrous tissue tunica media or middle layer of smooth muscle and elastic tissue tunica intima or inner lining of squamous epithelium called endothelium.

70. Arteries and arterioles The amount of muscular and elastic tissue varies in the arteries depending upon their size. In the large arteries, sometimes called elastic arteries, the tunica media consists of more elastic tissue and less smooth muscle. These proportions gradually change as the arteries branch many times and become smaller until in the arterioles (the smallest arteries) the tunica media consists almost entirely of smooth muscle. Arteries have thicker walls than veins and this enables them to withstand the high pressure of arterial blood.

71. Anastomoses and end-arteries Anastomoses are arteries that form a link between main arteries supplying an area, e.g. the arterial supply to the palms of the hand (p. 102) and soles of the feet, the brain, the joints and, to a limited extent, the heart muscle. If one artery supplying the area is occluded anastomotic arteries provide a collateral circulation. This is most likely to provide an adequate blood supply when the occlusion occurs gradually, giving the anastomotic arteries time to dilate End-arteries are the arteries with no anastomoses or those beyond the most distal anastomosis, e.g. the branches from the circulus arteriosus (circle of Willis) in the brain or the central artery to the retina of the eye. When an end-artery is occluded the tissues it supplies die because there is no alternative blood supply .

72. Veins and venules The veins are the blood vessels that return blood at low pressure to the heart. The walls of the veins are thinner than those of arteries but have the same three layers of tissue (Fig.5.3). They are thinner because there is less muscle and elastic tissue in the tunica media. When cut, the veins collapse while the thicker-walled arteries remain open. When an artery is cut blood spurts at high pressure while a slower, steady flow of blood escapes from a vein .

73. Some veins possess valves, which prevent backflow of blood , ensuring that it flows towards the heart (Fig. 5.4 ) Valves are abundant in the veins of the limbs, especially the lower limbs where blood must travel a considerable distance against gravity when the individual is standing. Valves are absent in very small and very large veins in the thorax and abdomen. They are formed by a fold of tunica intima strengthened by connective tissue. The cusps are semilunar in shape with the concavity towards the heart. The smallest veins are called venules .

74. Capillaries The smallest arterioles break up into a number of minute vessels called capillaries . Capillary walls consist of a single layer of endothelial cells through which water and other small-molecule substances can pass. Blood cells and large-molecule substances such as plasma proteins do not normally pass through capillary walls The capillaries form a vast network of tiny vessels which link the smallest arterioles to the smallest venules . Their diameter is approximately that of an erythrocyte (7 um). The capillary bed is the site of exchange of substances between the blood and the tissue fluid, which bathes the body cells.

75. S inusoids Sinusoids are wider than capillaries and have extremely thin walls separating blood from the neighbouring cells . In some there are distinct spaces between the endothelial cells . Among the endothelial cells there may be many phagocytic macrophages, e.g. Kupffer cells in the liver . Sinusoids are found in bone marrow, endocrine glands, spleen and liver. Because of their larger lumen the blood pressure in sinusoids is lower than in capillaries and there is a slower rate of blood flow.

76. Lymphatic System

77. PARTS AND FUNCTIONS OF LYMPHATIC SYSTEMS The lymphatic system is part of the vascular system  and an important part of the immune system , comprising a large network of lymphatic vessels  that carry a clear fluid called lymph   (directionally towards the  heart). Unlike the circulatory system, the lymphatic system is not a closed system. The human circulatory system processes an average of 20 litres of blood per day through capillary filtration, which removes  plasma while leaving the blood cells. Roughly 17 litres of the filtered plasma is reabsorbed directly into the blood vessels, while the remaining three litres remain in the interstitial fluid. One of the main functions of the lymph system is to provide an accessory return route to the blood for the surplus three litres .

78. TYPES OF LYMPHATIC ORGANS AND VESSELS: The primary or central lymphoid organs  Secondary or peripheral lymphoid organs Secondary lymphoid tissue Tertiary lymphoid organs  Thymus Spleen Lymph nodes Lymphatic vessels

79. Functions of Lymphatic Systems: The lymphatic system has multiple interrelated functions: It is responsible for the removal of interstitial fluid from tissues It absorbs and transports fatty acids and  fats as   chyle   ( milky bodily fluid that forms in the small intestine) from the digestive system It transports  white blood cells to and from the lymph nodes into the bones The lymph transports antigen-presenting cells , such as dendritic cells, to the lymph nodes where an immune response is stimulated.

80. Introduction Components Lymph is the fluid Vessels – lymphatics Structures & organs Functions Return tissue fluid to the bloodstream Transport fats from the digestive tract to the bloodstream Surveillance & defense

81. The Lymphatic System

82. Lymphatics Originate as lymph capillaries Capillaries unite to form larger vessels Resemble veins in structure Connect to lymph nodes at various intervals Lymphatics ultimately deliver lymph into 2 main channels Right lymphatic duct Drains right side of head & neck, right arm, right thorax Empties into the right subclavian vein Thoracic duct Drains the rest of the body Empties into the left subclavian vein

83. Lymph Capillaries

84. Lymphatic Vessels

85. Main Channels of Lymphatics

86. Major Lymphatic Vessels of the Trunk

87. Lymph Tissue 3 types Diffuse lymphatic tissue No capsule present Found in connective tissue of almost all organs Lymphatic nodules No capsule present Oval-shaped masses Found singly or in clusters Lymphatic organs Capsule present Lymph nodes, spleen, thymus gland

88. Lymph Nodules

89. Lymph Nodes Oval structures located along lymphatics Enclosed by a fibrous capsule Cortex = outer portion Germinal centers produce lymphocytes Medulla = inner portion Medullary cords Lymph enters nodes through afferent lymphatics, flows through sinuses, exits through efferent lymhpatic

90. Lymph Node

91. Tonsils Multiple groups of large lymphatic nodules Location – mucous membrane of the oral and pharyngeal cavities Palatine tonsils Posterior-lateral walls of the oropharynx Pharyngeal tonsil Posterior wall of nasopharynx Lingual tonsils Base of tongue

92. Tonsils

93. Spleen Largest lymphatic organ Located between the stomach & diaphragm Structure is similar to a node Capsule present But no afferent vessels or sinuses Histology Red pulp contains all the components of circulating blood White pulp is similar to lymphatic nodules Functions Filters blood Stores blood

94. Spleen

95. Thymus Gland Location – behind the sternum in the mediastinum The capsule divides it into 2 lobes Development Infant – conspicuous Puberty – maximum size Maturity – decreases in size Function Differentiation and maturation of T cells

96. Thymus Gland

97. Function of the Lymphatic System Defense against harmful organisms and chemicals 2 types of defense Nonspecific Specific Specific defense = immunity Humoral immunity involves B cells that become plasma cells which produce antibodies that bind with specific antigens. Cell-mediated immunity involves T cells that directly destroy foreign cells

98. Derivation and Distribution of Lymphocytes

99. Regulation Of Heart Rate The heart can beat on its own without any influence from outside stimulation thanks to the automatic pace-setter of your heart, known as the SA node. This is often nicknamed the 'pacemaker' of the heart . Heart rate is maintained within normal range constantly. It is subjected for variation during normal physiological conditions such as exercise, emotion, etc. However, under physiological conditions, the altered heart rate is quickly brought back to normal. It is because of the perfectly tuned regulatory mechanism in the body. Heart rate is regulated by the nervous mechanism , which consists of three components: A. Vasomotor center B. Motor (efferent) nerve fibers to the heart C. Sensory (afferent) nerve fibers from the heart .

100. Vasomotor Center – Cardiac Center Vasomotor center is the nervous center that regulates the heart rate. It is the same center in brain, which regulates the blood pressure. It is also called the cardiac center . Vasomotor center is bilaterally situated in the reticular formation of medulla oblongata and lower part of pons. Areas of Vasomotor Center Vasomotor center is formed by three areas : 1 . Vasoconstrictor area- increases the heart rate by sending accelerator impulses to heart, through sympathetic nerves 2 . Vasodilator area- decreases the heart rate by sending inhibitory impulses to heart through vagus nerve. 3 . Sensory area- Sensory area receives sensory impulse via glosso ­ pharyngeal nerve and vagus nerve from periphery, particularly , from the baroreceptors. In turn, this area controls the vasoconstrictor and vasodilator areas.

101. Motor (Efferent) Nerve Fibers To Heart Heart receives efferent nerves from both the divisions of autonomic nervous system. Parasympathetic fibers arise from the medulla oblongata and pass through vagus nerve . Sympathetic fibers arise from upper thoracic (T1 to T4) segments of spinal cord (Fig. 1011 ).

102. Sensory (Afferent) Nerve Fibers From Heart Afferent (sensory) nerve fibers from the heart pass through inferior cervical sympathetic nerve . These nerve fibers carry sensations of stretch and pain from the heart to brain via spinal cord .

103. Arterial blood pressure varies even under physiological conditions . However, immediately it is brought back to normal level because of the presence of well organized regulatory mechanisms in the body . Body has four such regulatory mechanisms to maintain the blood pressure within normal limits (Fig. 103.2): Nervous mechanism or short-term regulatory mechanism Renal mechanism or long-term regulatory mechanism Hormonal mechanism Local mechanism Regulation of (Arterial) Blood Pressure

104. Nervous Mechanism For Regulation Of Blood Pressure – Short-term Regulation Nervous regulation is rapid among all the mechanisms involved in the regulation of arterial blood pressure. When the pressure is altered, nervous system brings the pressure back to normal within few minutes. Although nervous mechanism is quick in action, it operates only for a short period and then it adapts to the new pressure. Hence, it is called short-term regulation . The nervous mechanism regulating the arterial blood pressure operates through the vasomotor system (medulla oblongata). Vasomotor System Vasomotor system includes three components: 1. Vasomotor center 2. Vasoconstrictor fibers 3. Vasodilator fibers.

105. Vasomotor center regulates the arterial blood pressure by causing vasoconstriction or vasodilatation . However, its actions depend upon the impulses it receives from other structures such as baroreceptors, chemoreceptors, higher centers and respiratory centers. Baroreceptors Mechanism:

106. Renal Mechanism For Regulation Of Blood Pressure – Long-term Regulation Kidneys play an important role in the long-term regulation of arterial blood pressure. When blood pressure alters slowly in several days/months/years, the nervous mechanism adapts to the altered pressure and looses the sensitivity for the changes. It cannot regulate the pressure any more. In such conditions, the renal mechanism operates efficiently to regulate the blood pressure . Therefore, it is called long-term regulation . Kidneys regulate arterial blood pressure by two ways : 1. By regulation of ECF volume 2. Through renin angiotensin mechanism.

107. By Regulation Of Extracellular Fluid Volume When the blood pressure increases, kidneys excrete large amounts of water and salt, particularly sodium, by means of pressure diuresis and pressure natriuresis . Pressure diuresis is the excretion of large quantity of water in urine because of increased blood pressure. Even a slight increase in blood pressure doubles the water excretion. Pressure natriuresis is the excretion of large quantity of sodium in urine. Because of diuresis and natriuresis , there is a decrease in ECF volume and blood volume, which in turn brings the arterial blood pressure back to normal level .

108. Through Renin-angiotensin Mechanism Angiotensin-converting enzyme- ACE

109. Hormonal mechanism